Mercedes is expecting just three engine manufacturers to continue in Formula One when the new V6 turbo regulations are introduced in 2014.

The teams are set to switch from the current 2.4-litre V8s to 1.6-litre V6s in 2014 with a greater emphasis on energy recovery systems such as KERS. Ferrari, Renault and Mercedes are all developing engines under the new regulations, while Cosworth has remained quieter about its plans and newcomers PURE recently revealed to Autosport that it has suspended operations.

Mercedes motorsport boss Norbert Haug believes the sport will enter the new era with just three engine brands on the grid.

"I assume and think and am pretty sure that we will have three and no more than three," he said. "But with three I think we can get the job done."

When asked if Mercedes is therefore looking to increase the number of teams it supplies, Haug added: "We need to evaluate the situation. We are in discussions with the three manufacturers together - still on cost issues and bringing the costs down. And this will also be the object, who will supply whom."

Bernie Ecclestone said he was "sure" three manufacturers would be enough to supply all 12 teams in 2014, although the original intention of the regulations had been to attract more big-name manufacturers.

However, Racecar Engineering reported last month that the 2014 regulations for the LMP1 class in endurance racing could change to allow F1 engines to compete at the famous Le Mans 24 Hours alongside 5-litre turbos. Audi and Toyota are currently competing in LMP1 with Porsche set to return in 2014, but it may be more likely that F1 engine manufacturers use LMP1 as a test bed for their F1 engines.